Powder coating compositions for use in painting are extremely desirable. Such coating compositions greatly reduce and can even eliminate the organic solvents used in liquid paints. When the powder coating composition is cured by heating, little, if any, volatile material is given off to the surrounding environment. This is a significant advantage over liquid paints in which organic solvent is volatilized into the surrounding atmosphere when the paint is cured by heating.
For exterior durability, the powder coating composition is usually formulated with an acrylic polymer. One common curing mechanism for obtaining powder coating compositions with good exterior durability is based on reaction between an acid group-containing acrylic polymer and a triglycidyl isocyanurate (TGIC) curing agent. Although powder coating compositions using these materials give coatings with good exterior durability, they are expensive to formulate because of the TGIC, often have poor stability, and often give coatings which are deficient in other physical properties.